| 1 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 2 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Dec 2024 |
| 3 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 4 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Dec 2024 |
| 5 | Martino, Joseph C. | Pasadena, TX 77504 | Oil & Gas Operator | Dec 2024 |
| 6 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Dec 2024 |
| 7 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 8 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 9 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Dec 2024 |
| 10 | McRae, Nathan Rathburn | Hebbronville, TX 78361 | Oil & Gas Operator | Apr 1994 |
| 11 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2024 |
| 12 | Mestena Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 2015 |
| 13 | Mestena Operating, LTD. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jun 2009 |
| 14 | Mestena, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Nov 2001 |
| 15 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 16 | Mir-Tex Energy Corp. | Mirando City, TX 78369 | Oil & Gas Operator | Aug 2003 |
| 17 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 18 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Dec 2024 |
| 19 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 20 | Monitor O&G, L.L.C. | Frisco, TX 75034 | Oil & Gas Operator | Jan 2016 |
| 21 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 22 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2024 |
| 23 | Mustang Oil & Gas Corporation | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2021 |